Fuel gauge issues?

[plumcrazy]

Ok, my first winter project is my fuel gauge. The gauge never registered anything since I've owned it, found 12V wasn't present at guage cluster, hooked up 12v to proper post, then gauge registered past full. The up side is the guage lights then worked. The repair manual just says " replace sending unit". What am I missing? What else can I do to verify that the problem is the sending unit, ground, gauge, ect.

 

[BrockGrimes]

Ok, my first winter project is my fuel gauge. The gauge never registered anything since I've owned it, found 12V wasn't present at guage cluster, hooked up 12v to proper post, then gauge registered past full. The up side is the guage lights then worked. The repair manual just says " replace sending unit". What am I missing? What else can I do to verify that the problem is the sending unit, ground, gauge, ect.

See the guage section in the first post:
http://www.jeep-cj.com/forums/f49/useful-info-thought-id-share-665/

 

[BajaEdition]

great article Brock, And I like the place it states that you need to check your grounds, after all the vehicle is over 20 years old. Yep, ground connections rust. sending units work by resistance, hence rusty connections, more resistance. great place to start.

 

[plumcrazy]

Great page, thanks Brock. If I'm reading it right, without a good it possible for the gauge to show full, right?

 

[rushpowersystems]

The fact that your gauge is pegged tells me your sending wire is grounded, unhook it from the gauge and you should see it drop back down with the key on. If so reattach the wire to the gauge and unplug it from the sending unit. If it is still pegged you have wiring problems, if it drops, again with the key on, it’s in your sending unit. The float may be stuck at the top of the tank or the sending unit may be bad, either way you are going to need to drop the tank and inspect it.

 

[plumcrazy]

I was trying to get out of dropping the tank. Those bolts look like they are ready for a fight. I guess I really should drop it for a good inspection of everything in that area.

A guestion for those of you that have pulled your tanks, do you just remove 4 or 5 bolts accross the back along the bottom of the bumper area, or are the just for the shield? I'm sure I'll figure it out once I get into it, just looking for someone to say " it's not that bad of a job".

 

[hole]

Its not that bad of a job You asked for it. Seriously, it really isnt. Try and run it out of fuel first to lighten it up. I would also recommend spraying penetrating lube on all the bolts/nuts the day before. While the tank is down, change all the hose'es , including the filler and vent.

 

[IOPort51]

I was trying to get out of dropping the tank. Those bolts look like they are ready for a fight. I guess I really should drop it for a good inspection of everything in that area.

A guestion for those of you that have pulled your tanks, do you just remove 4 or 5 bolts accross the back along the bottom of the bumper area, or are the just for the shield? I'm sure I'll figure it out once I get into it, just looking for someone to say " it's not that bad of a job".

wear goggles!!
the center bolt in the back is for the shield and can remain in place.

 

[plumcrazy]

Thanks guys, it's next on the "To do list".

 

[ColoradoCJ7]

Great discussion, on the same topic.

If the gauge is registering the wrong amount I assume that would tend to point more to a sending unit issue than a grounding problem, does that sound right?

Mine shows half full when it is actually empty, 3/4 when it is half full, etc.

Just looking for some suggestions.

 

[BajaEdition]

Great discussion, on the same topic.

If the gauge is registering the wrong amount I assume that would tend to point more to a sending unit issue than a grounding problem, does that sound right?

Mine shows half full when it is actually empty, 3/4 when it is half full, etc.

Just looking for some suggestions.

that sounds like a bad sending unit, instead of a ground. a sending unit is a variable resister, when full there is a small amount of resistance, when empty there is a lot of resistance so what is happening there is not right

 

[ColoradoCJ7]

that sounds like a bad sending unit, instead of a ground. a sending unit is a variable resister, when full there is a small amount of resistance, when empty there is a lot of resistance so what is happening there is not right

That is what I thought, time to break out the tools.

I appreciate the info!